Preparation of multi-walled carbon nanotube supported TiO2 and its photocatalytic activity in the reduction of CO2 with H2O

Multi-walled carbon nanotube (MWCNT) supported TiO2 composite catalysts were prepared by sol–gel and hydrothermal methods. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy and N2-adsorption analysis were carried out to characterize the composite catalysts. In using the sol–gel method, the MWCNTs were coated with anatase TiO2 nanoparticles, and by the hydrothermal method, rutile TiO2 nanorods were uniformly deposited on the MWCNTs. The photocatalytic activities of the composite catalysts were evaluated by the reduction of CO2 with H2O. The results indicate that the addition of an appropriate amount of MWCNTs as supports for TiO2 could remarkably improve the efficiency of the photocatalytic reaction. The composite catalysts prepared by the sol–gel method lead to the main formation of C2H5OH, while HCOOH is found to be the major product on the sample prepared by the hydrothermal method.